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Making the water softer without an RO device? any tips?

0

Hi all,

ive just signed up to this forum so apologies if ive posted in the wrong place...

Im starting up a 300L aquarium and am looking at keeping a number of various discus species together, ive done some research and understand that the gH of the water needs to be very soft (1-3gh, at the moment im looking at Gh of 7-9). the research seems to be pointing me in the direction of RO mechanisms and deionisation etc however this is costly and fundage isnt permitting this at the moment. I read about drift wood being able to soften water and i do have a small amount in the tank however, further research led me to a water softener pillow (which i have purchased and is in place in my filter) - my understanding is that it takes out calcium and magnesium in order to make the water softer however it does this by replacing with sodium ions...

this is now where i have questions;

1) is the increase in sodium ions going to be harmful to the discus?
2) is there any other way of making the water softer without RO? (ive read about using distilled water (purchasable from local hardware store) with added dicus minerals - is this a feasible option to RO?)

i havent got any fish in the tank at all at the moment as i want to get the water conditions absolutely stable before i introduce any discus.

A 300 liter tank is just 79 gallons meaning, at best, it can hold eight discus. As for different 'species, that is not acceptable since the two main species require vastly different pH's to do well. I assume you mean different 'strains'. Different strains really do fine together.

You absolutely canNOT use wood to 'soften' water to any degree that matters, much less on a continuous bases. Never use 'distilled water' alone (same for RO.) Water with near zero minerals is deadly for fish. Besides, with the daily massive water changes discus require, a RO system is vastly cheaper than using such large volumes of DW. An intank water softener will fail quickly and replacement costs will add up very fast with all the WC. Don't see that working on a cost bases - using RO and local water looks to be the most cost effective if you want to breed. Otherwise, why bother?.

Unless you are breeding, soft water is totally unnecessary to keep healthy and happy discus. The key to keeping discus is one simple rule - large water changes (NO less than 100% per week and if you want to breed, near 100% every single day.) The test for good water conditions is nitrates below 0.2 ppm at all times (note: this is for keeping, not breeding. Those levels are far too high for most discus to breed.)

AS for sodium, well, when my discus are off for any reason, adding salt is great for discus - of course, it is fresh water aquarium salt and I replace the amount lost by water changes. While I have never used salt for more than two weeks, some experts use salt for old discus regularly. Never do that for young/growing discus unless they are sick.)

Another point: temperature. Discus require a minimum tank temperature of 84 F (29 C) and 86-88 F (30 - 31 C) is better. Avoid live food except brine shrimp. Frozen should be sterilized by the mfg. There are great pellets sold and this is cheaper than live (which can be fed as a treat.)

Last edited by Cermet; 10-06-2013 at 12:06 PM.

Knowledge is fun(damental)

A 75 gal with eight Discus, fake plants, and a lot of wood also with sand substrate. Clean up crew is down to just two Sterba's Corys. Filters: continuous new water flow; canister w/UV, in-tank algae scrubber!! Finally, junked the nitrate removal unit from hell.

Sodium is harmful to all soft water fish in varying degrees; hard water fish are able to tolerate it to some extent, but not soft water fish of which discus is one. When it comes to treatment for some specific issue, salt is the last method that should be used with soft water fish; there will usually be better and safer treatments. I have posted my article on salt and its effects on fish elsewhere, so will leave this issue.

Turning to the technical issue of softening water. The only safe way to soften hard water is by dilution with "pure" water such as RO or distilled, or rainwater if it is otherwise safe in your area. If the tap water does not contain something really harmful, like high nitrates for example, mixing it with "pure" water to reduce the GH and pH is fairly straightforward. Only if the tap is un-usable to begin with is it necessary to use exclusively RO water with specific trace minerals added.

However, in your case I do not see the need for such drastic measures. A GH of 7 dGH is not at all bad, and if it does get to 9 you could dilute it a bit with rainwater or pure water.

Wood, dry leaves, peat and similar natural substances will soften water, but this will either not be by much (in the case of wood especially), or it will not last long (leaves, peat), depending upon the initial GH and the volume of water and substances.

Now, having said all that for the technical side, we turn to your proposed discus. These fish will likely have been commercially raised, not wild caught, and the water parameters of the breeder is what you want to know and aim for, or close.

Hope this helps.

Byron Hosking, BMus, MA
Vancouver, BC, Canada

Something we all need to remember: The fish you've acquired was quite happy not being owned by you, minding its own business. If you’re going to take it under your wing then you’re responsible for it. Every aspect of its life is under your control, from water quality and temperature to swimming space. [Nathan Hill in PFK]

Many experts suggest salt as a treatment for discus - even in older discus books; also, salt is used all the time for specific illnesses on many freshwater fish. I have had fantastic success with salt in treating sick discus. It is vastly superior to all other treatments I've tried in the past.

Whether it is correct for a specific fish illness/discus or even when to use, depends on conditions and knowledge of the person but it is fact that salt is good for discus under many conditions.

That said, discus NEVER see salt in their natural environment but neither do they see the huge phosphates levels, nor vast levels of bacteria, and all too often way too high nitrate levels common in all aquariums. But fish use their gills not just to breath but to pass waste to the water - the gills function much as our kidney's. Hence, by lowing the osmotic pressure on their gills by adding aquarium safe salt, their levels of waste are more easily transferred to the aquarium water. In the wild this is never an issue since nitrates/phosphates are so low as to be irrelevant.

Many professionals use salt for discus. Books recommend it for discus. I’ve used it and the science supports its use. Of course, the vast majority of discus keepers prefer to use shotgun medication on their fish ($$$) and as we all know and have learned, money fixes all issues … lol.

Again, what Byron is saying in general is valid and I am not saying use salt. Just that salt is not dangerous to discus. It is useful when discus are ill or just not eating. Then careful use can achieve results. As in all treatments - knowledge and the do no harm principle should be your guild - just wish more discus keepers learned that lesion before hitting their fish with every med they can buy ... .

Last edited by Cermet; 10-06-2013 at 05:21 PM.

Knowledge is fun(damental)

A 75 gal with eight Discus, fake plants, and a lot of wood also with sand substrate. Clean up crew is down to just two Sterba's Corys. Filters: continuous new water flow; canister w/UV, in-tank algae scrubber!! Finally, junked the nitrate removal unit from hell.

I will now cite my entire article, as there are some serious errors in the reasoning mentioned above. There are references at the end with the sources for my information, so this is not something I made up but proven science. I like to have the facts out there, then everyone can make informed decisions.

Many fish stores, and other “sources of wisdom” about fishkeeping, will recommend salt as a general "tonic" for freshwater tropical fish. The usual suggested dosage of salt is something like a teaspoon per 5 gallons. As David A. Lass points out, there is not much therapeutic benefit at those dosages. “Salt serves more to assuage the hobbyist's need to ‘do something’ for their tropical fish,” he writes. [8] There is absolutely no need to add salt to freshwater aquaria except as a specific treatment, and even here the sensitivity of certain fish species must be kept in mind. Fish health expert Dr Peter Burgess says he certainly doesn't advocate salt for permanent use: "Unless the species has a natural requirement for salt, then we should not add salt to an aquarium (or pond).” [1]

As the scientific data presented in this summary article indicates, adding salt to a freshwater aquarium on a regular basis will, at best, do nothing of any value at all. But at worst, it will stress salt-intolerant fish, making them more vulnerable to disease and less likely to live a healthy and normal lifespan. To understand why, we need to understand what salt does in water, and how fish are affected. But before this, we must clarify just what we mean by “salt.”

Sodium chloride

In chemistry, salts are ionic compounds that result from the neutralization reaction of an acid and a base. They are composed of cations (positively charged ions) and anions (negative ions) so that the product is electrically neutral (without a net charge) [Wikipedia, definition of “Salt (chemistry)”]. There are mineral salts for most minerals. But for the purpose of this article, we are dealing solely with common salt—what we know as table salt, or rock salt, or aquarium salt. This salt is a mineral that is composed primarily of sodium chloride (NaCl), a chemical compound belonging to the larger class of ionic salts. It is essential for animal life in small quantities, but it is harmful to animals and plants in excess. Marine salt has other minerals in it too, but it is still “salt” for the purpose of this discussion.

Salt is an irritant, which causes the fish to secrete more mucus particularly in the gills where osmoregulation is occurring. And if salt is not predissolved carefully, it can give fish bad burns; this is especially true for scaleless fish, such as loaches, many catfish and some types of eels. [9]

Salt makes the water denser than the same water without salt. The aquarium contains water. The bodies of fish and plant leaves also contain water, just as we do—humans are approximately 70% water. The water in the aquarium and the water in the fish/plant are separated by a semi-permeable layer which is the cell. Water can and continually does pass through this cell; fish do not “drink” because they don’t have to in order to take in water. When either body of water is denser, the other less-dense body of water will pass through the membrane to equalize the water on both sides. The fish must control this process through what is termed osmoregulation.

Freshwater Fish Physiology

Salt definitely interferes with the osmotic regulation of fish and plants. It should be left alone; nature regulated that part itself, by creating freshwater, brackish and saltwater fish. The vast majority of freshwater fish live in waters having no measurable salinity, and this has been crucial in the evolution of their physiology. Fresh water fish differ physiologically from salt water fish in several respects: their gills must be able to diffuse dissolved gasses while keeping the salts in the body fluids inside; their scales reduce water diffusion through the skin; and they also have well developed kidneys to reclaim salts from body fluids before excretion.

Freshwater fish have physiological mechanisms that permit them to concentrate salts within their bodies in a salt-deficient environment; marine fish, on the other hand, excrete excess salts in a hypertonic environment. Fish that live in both environments retain both mechanisms. Freshwater fish concentrate salts to compensate for their low salinity environment. They produce very dilute but copious urine—up to a third of their body weight each day—to rid themselves of excess water, while conducting active uptake of ions at the gills. [2]

The kidneys of freshwater fish have two functions: osmoregulation [discussed below] and hematopoiesis, which is the formation of blood celular components. Each fish species is adapted to the range of salts in its habitat water, and the kidneys function well within that range. The kidneys have to work harder whenever the salt content of the water in which the fish is living is greater than that of the fish’s preference, i.e., the natural habitat. The closer the water is to the species’ requirements, the easier it will be for the fish to maintain proper osmotic levels. One of the myths about the “benefit” of regular addition of salt is that it allegedly maintains an osmoregulatory balance; in point of fact, regular use of salt has the exact opposite effect and can cause bloating due to an osmotic imbalance. [3]

Osmoregulation is the technical term for the physiological mechanism fish use to control the amount of salt and water in their bodily fluids. As the name suggests, it's based on osmosis. Water is constantly passing through the cells of freshwater fish by osmosis in an attempt to equate the water inside the fish with the water in the aquarium. Freshwater fish regularly excrete this water through respiration and urination; the average fish will urinate 30% of its body mass every day. The more salt in the aquarium water, the greater the strain on the fish's kidneys, which in turn adds to the fish's stress in attempting to maintain their internal stability.

And salinity affects the amount of energy the fish must spend to maintain the physiological equilibrium—the complex chain of internal chemical reactions that keep the pH of the fish’s blood steady, its tissues fed, and the immune system functioning. When salinity increases beyond what the fish is designed by nature to handle, the fish must work harder and use more energy just to “keep going.” Laura Muha [4] likens this to driving a car up a steep hill—it takes more energy (gas) to maintain the same speed as driving on level ground, and it causes more “wear and tear.” This increased energy output is wearing down the fish, and the fish is not able to expend this crucial energy on other important functions. The growth rate is affected, a shorter lifespan will usually result, and there will be increased risk of various health problems along the way.

Fish and plants from mineral-poor waters do not appreciate being kept in slightly saline water conditions. Many of the most popular fish today, like cardinal tetra and rasbora, come from soft water habitats. Short term exposure to low salt concentrations across a few days or a couple of weeks may not do them major harm, but constant use of salt in their aquaria could cause problems. [5] In Weitzman et al. (1996), the authors mention that 100 ppm of salt is the maximum that can be tolerated by most characins, and some species show considerable stress leading to death at a level of 60 ppm. [6] To put this in perspective, 100 ppm is approximately equal to 0.38 gram of salt per gallon of water. One level teaspoon holds approximately six grams of salt, so just 1 teaspoon of salt in 16 gallons of water will cause stress, and in some species lead to death.

Another problem is that salt increases the total dissolved solids [TDS] in the water. An aquarium treated with one teaspoon of salt per gallon of water will have an established dose of 2400 ppm. Add to this the TDS occurring from calcium and magnesium salts [these make water “hard”], water conditioners and other additives, and you can end up with over 3000 ppm of TDS. [10] This is intolerable for most fish; even the very hard water in the African rift lakes does not contain more than 600 ppm TDS. And for fish from naturally soft and acidic water environments, this is very dangerous, for nowhere in nature does acidic water exist with a level of TDS anywhere near this. And the deviation from normal osmotic pressure that this creates is very harmful to all fish.

Keeping the tank salty all the time will not help with disease resistance in freshwater fish; in fact, it will actually increase the fishes’ susceptibility to disease and parasites by keeping the fish somewhat stressed all the time, and this weakens the immune system. And at the low level of salt generally recommended for these so-called benefits, there will be no benefit that cannot be achieved solely with regular water changes using a good conditioner.

Some concluding thoughts...

Using salt to increase water hardness

Although plain aquarium/tonic salt (sodium chloride) is sometimes suggested as a good way to increase hardness and improve buffering, it in fact provides very little of either. Marine salt mix, on the other hand, will raise the pH and carbonate hardness quite significantly. But it also raises the salinity, something most freshwater fish do not appreciate. If you live in a soft water area and want to keep hard water fish, using marine salt mix is not really a viable option. Rift Valley cichlids, in particular, seem to be peculiarly sensitive to salt, and elevated salinity levels have been identified as one factor responsible for the dropsy-like disease known as Malawi Bloat (Andrews, et al. 1988). [7]

Fish lore also has it that salt is good for use with mollies, other livebearers and goldfish. David Lass [8] notes that the vast majority of livebearers, including mollies of all types and colors, and sailfins, come from the Far East. They have been raised for generations in water that is moderately hard, and of neutral pH. These tropical fish are very far removed from the wild mollies that came from brackish water. All of the sailfin and lyretail mollies, balloon bellies, blacks, reds, and dalmations do fine without salt. The same with goldfish. The main confusion is that tropical fish need alkalinity. Salt is just one part of alkalinity.

Although NaCl is not composed of any truly "hard" ions, it does raise the total dissolved solids in the water, and these contribute to raise general hardness. This is not well tolerated by a number of fish, especially true softwater fish from places like the Amazon River basin, where there are very few electrolytes of any kind in the water. Salt can have an unpredictable effect on softwater fish, since there are no bodies of water in Nature which are naturally saline (high in NaCl) while being very low in "true" hardness ion concentration (calcium, magnesium, potassium, etc.). [9]

Salt and Plants: When salt is added to the aquarium water, the water inside the plant cells is less dense so it escapes through the cells. The result is that the plant literally dries out, and will wilt. I've so far been unable to find a measurement of how much salt will be detrimental to plants; all authorities I have found do note that some species are more sensitive than others, and all recommend no salt in planted aquaria.

Domestic water softeners: Domestic water softeners do not produce soft water in the sense that aquarists mean. What domestic water softeners do is remove the temporary hardness (such as carbonates) that potentially furs up pipes and heaters by replacing it with permanent hardness (such as chlorides) that does not. While you can pass this softened water through a reverse-osmosis filter to remove the permanent hardness as well, until you have done so, you shouldn't consider the softened water as being suitable for soft water fish.

In fact, aquarists are divided on whether the resulting softened water is safe for keeping fish at all. The odd balance of minerals in softened water is not typical of any of the environments from which tropical fish are collected. While the chloride levels are much higher than those soft water fish are adapted to, the levels of carbonate hardness are too low for the health of hard water fishes like Rift Valley cichlids, goldfish, and livebearers. So the safe approach is not to use it in any aquarium, and instead draw water from the unsoftened drinking water source in the kitchen. [7]

Something we all need to remember: The fish you've acquired was quite happy not being owned by you, minding its own business. If you’re going to take it under your wing then you’re responsible for it. Every aspect of its life is under your control, from water quality and temperature to swimming space. [Nathan Hill in PFK]

I will now cite my entire article, as there are some serious errors in the reasoning mentioned above. There are references at the end with the sources for my information, so this is not something I made up but proven science. I like to have the facts out there, then everyone can make informed decisions.

Many fish stores, and other “sources of wisdom” about fishkeeping, will recommend salt as a general "tonic" for freshwater tropical fish. The usual suggested dosage of salt is something like a teaspoon per 5 gallons. As David A. Lass points out, there is not much therapeutic benefit at those dosages. “Salt serves more to assuage the hobbyist's need to ‘do something’ for their tropical fish,” he writes. [8] There is absolutely no need to add salt to freshwater aquaria except as a specific treatment, and even here the sensitivity of certain fish species must be kept in mind. Fish health expert Dr Peter Burgess says he certainly doesn't advocate salt for permanent use: "Unless the species has a natural requirement for salt, then we should not add salt to an aquarium (or pond).” [1]

As the scientific data presented in this summary article indicates, adding salt to a freshwater aquarium on a regular basis will, at best, do nothing of any value at all. But at worst, it will stress salt-intolerant fish, making them more vulnerable to disease and less likely to live a healthy and normal lifespan. To understand why, we need to understand what salt does in water, and how fish are affected. But before this, we must clarify just what we mean by “salt.”

Sodium chloride

In chemistry, salts are ionic compounds that result from the neutralization reaction of an acid and a base. They are composed of cations (positively charged ions) and anions (negative ions) so that the product is electrically neutral (without a net charge) [Wikipedia, definition of “Salt (chemistry)”]. There are mineral salts for most minerals. But for the purpose of this article, we are dealing solely with common salt—what we know as table salt, or rock salt, or aquarium salt. This salt is a mineral that is composed primarily of sodium chloride (NaCl), a chemical compound belonging to the larger class of ionic salts. It is essential for animal life in small quantities, but it is harmful to animals and plants in excess. Marine salt has other minerals in it too, but it is still “salt” for the purpose of this discussion.

Salt is an irritant, which causes the fish to secrete more mucus particularly in the gills where osmoregulation is occurring. And if salt is not predissolved carefully, it can give fish bad burns; this is especially true for scaleless fish, such as loaches, many catfish and some types of eels. [9]

Salt makes the water denser than the same water without salt. The aquarium contains water. The bodies of fish and plant leaves also contain water, just as we do—humans are approximately 70% water. The water in the aquarium and the water in the fish/plant are separated by a semi-permeable layer which is the cell. Water can and continually does pass through this cell; fish do not “drink” because they don’t have to in order to take in water. When either body of water is denser, the other less-dense body of water will pass through the membrane to equalize the water on both sides. The fish must control this process through what is termed osmoregulation.

Freshwater Fish Physiology

Salt definitely interferes with the osmotic regulation of fish and plants. It should be left alone; nature regulated that part itself, by creating freshwater, brackish and saltwater fish. The vast majority of freshwater fish live in waters having no measurable salinity, and this has been crucial in the evolution of their physiology. Fresh water fish differ physiologically from salt water fish in several respects: their gills must be able to diffuse dissolved gasses while keeping the salts in the body fluids inside; their scales reduce water diffusion through the skin; and they also have well developed kidneys to reclaim salts from body fluids before excretion.

Freshwater fish have physiological mechanisms that permit them to concentrate salts within their bodies in a salt-deficient environment; marine fish, on the other hand, excrete excess salts in a hypertonic environment. Fish that live in both environments retain both mechanisms. Freshwater fish concentrate salts to compensate for their low salinity environment. They produce very dilute but copious urine—up to a third of their body weight each day—to rid themselves of excess water, while conducting active uptake of ions at the gills. [2]

The kidneys of freshwater fish have two functions: osmoregulation [discussed below] and hematopoiesis, which is the formation of blood celular components. Each fish species is adapted to the range of salts in its habitat water, and the kidneys function well within that range. The kidneys have to work harder whenever the salt content of the water in which the fish is living is greater than that of the fish’s preference, i.e., the natural habitat. The closer the water is to the species’ requirements, the easier it will be for the fish to maintain proper osmotic levels. One of the myths about the “benefit” of regular addition of salt is that it allegedly maintains an osmoregulatory balance; in point of fact, regular use of salt has the exact opposite effect and can cause bloating due to an osmotic imbalance. [3]

Osmoregulation is the technical term for the physiological mechanism fish use to control the amount of salt and water in their bodily fluids. As the name suggests, it's based on osmosis. Water is constantly passing through the cells of freshwater fish by osmosis in an attempt to equate the water inside the fish with the water in the aquarium. Freshwater fish regularly excrete this water through respiration and urination; the average fish will urinate 30% of its body mass every day. The more salt in the aquarium water, the greater the strain on the fish's kidneys, which in turn adds to the fish's stress in attempting to maintain their internal stability.

And salinity affects the amount of energy the fish must spend to maintain the physiological equilibrium—the complex chain of internal chemical reactions that keep the pH of the fish’s blood steady, its tissues fed, and the immune system functioning. When salinity increases beyond what the fish is designed by nature to handle, the fish must work harder and use more energy just to “keep going.” Laura Muha [4] likens this to driving a car up a steep hill—it takes more energy (gas) to maintain the same speed as driving on level ground, and it causes more “wear and tear.” This increased energy output is wearing down the fish, and the fish is not able to expend this crucial energy on other important functions. The growth rate is affected, a shorter lifespan will usually result, and there will be increased risk of various health problems along the way.

Fish and plants from mineral-poor waters do not appreciate being kept in slightly saline water conditions. Many of the most popular fish today, like cardinal tetra and rasbora, come from soft water habitats. Short term exposure to low salt concentrations across a few days or a couple of weeks may not do them major harm, but constant use of salt in their aquaria could cause problems. [5] In Weitzman et al. (1996), the authors mention that 100 ppm of salt is the maximum that can be tolerated by most characins, and some species show considerable stress leading to death at a level of 60 ppm. [6] To put this in perspective, 100 ppm is approximately equal to 0.38 gram of salt per gallon of water. One level teaspoon holds approximately six grams of salt, so just 1 teaspoon of salt in 16 gallons of water will cause stress, and in some species lead to death.

Another problem is that salt increases the total dissolved solids [TDS] in the water. An aquarium treated with one teaspoon of salt per gallon of water will have an established dose of 2400 ppm. Add to this the TDS occurring from calcium and magnesium salts [these make water “hard”], water conditioners and other additives, and you can end up with over 3000 ppm of TDS. [10] This is intolerable for most fish; even the very hard water in the African rift lakes does not contain more than 600 ppm TDS. And for fish from naturally soft and acidic water environments, this is very dangerous, for nowhere in nature does acidic water exist with a level of TDS anywhere near this. And the deviation from normal osmotic pressure that this creates is very harmful to all fish.

Keeping the tank salty all the time will not help with disease resistance in freshwater fish; in fact, it will actually increase the fishes’ susceptibility to disease and parasites by keeping the fish somewhat stressed all the time, and this weakens the immune system. And at the low level of salt generally recommended for these so-called benefits, there will be no benefit that cannot be achieved solely with regular water changes using a good conditioner.

Some concluding thoughts...

Using salt to increase water hardness

Although plain aquarium/tonic salt (sodium chloride) is sometimes suggested as a good way to increase hardness and improve buffering, it in fact provides very little of either. Marine salt mix, on the other hand, will raise the pH and carbonate hardness quite significantly. But it also raises the salinity, something most freshwater fish do not appreciate. If you live in a soft water area and want to keep hard water fish, using marine salt mix is not really a viable option. Rift Valley cichlids, in particular, seem to be peculiarly sensitive to salt, and elevated salinity levels have been identified as one factor responsible for the dropsy-like disease known as Malawi Bloat (Andrews, et al. 1988). [7]

Fish lore also has it that salt is good for use with mollies, other livebearers and goldfish. David Lass [8] notes that the vast majority of livebearers, including mollies of all types and colors, and sailfins, come from the Far East. They have been raised for generations in water that is moderately hard, and of neutral pH. These tropical fish are very far removed from the wild mollies that came from brackish water. All of the sailfin and lyretail mollies, balloon bellies, blacks, reds, and dalmations do fine without salt. The same with goldfish. The main confusion is that tropical fish need alkalinity. Salt is just one part of alkalinity.

Although NaCl is not composed of any truly "hard" ions, it does raise the total dissolved solids in the water, and these contribute to raise general hardness. This is not well tolerated by a number of fish, especially true softwater fish from places like the Amazon River basin, where there are very few electrolytes of any kind in the water. Salt can have an unpredictable effect on softwater fish, since there are no bodies of water in Nature which are naturally saline (high in NaCl) while being very low in "true" hardness ion concentration (calcium, magnesium, potassium, etc.). [9]

Salt and Plants: When salt is added to the aquarium water, the water inside the plant cells is less dense so it escapes through the cells. The result is that the plant literally dries out, and will wilt. I've so far been unable to find a measurement of how much salt will be detrimental to plants; all authorities I have found do note that some species are more sensitive than others, and all recommend no salt in planted aquaria.

Domestic water softeners: Domestic water softeners do not produce soft water in the sense that aquarists mean. What domestic water softeners do is remove the temporary hardness (such as carbonates) that potentially furs up pipes and heaters by replacing it with permanent hardness (such as chlorides) that does not. While you can pass this softened water through a reverse-osmosis filter to remove the permanent hardness as well, until you have done so, you shouldn't consider the softened water as being suitable for soft water fish.

In fact, aquarists are divided on whether the resulting softened water is safe for keeping fish at all. The odd balance of minerals in softened water is not typical of any of the environments from which tropical fish are collected. While the chloride levels are much higher than those soft water fish are adapted to, the levels of carbonate hardness are too low for the health of hard water fishes like Rift Valley cichlids, goldfish, and livebearers. So the safe approach is not to use it in any aquarium, and instead draw water from the unsoftened drinking water source in the kitchen. [7]

Something we all need to remember: The fish you've acquired was quite happy not being owned by you, minding its own business. If you’re going to take it under your wing then you’re responsible for it. Every aspect of its life is under your control, from water quality and temperature to swimming space. [Nathan Hill in PFK]

1) is the increase in sodium ions going to be harmful to the discus?
2) is there any other way of making the water softer without RO? (ive read about using distilled water (purchasable from local hardware store) with added dicus minerals - is this a feasible option to RO?)

i havent got any fish in the tank at all at the moment as i want to get the water conditions absolutely stable before i introduce any discus.

any help would be greatly appreciated

1. Yes
2. No, not really. I buy RO water in bulk from a window cleaner, pay 2 euros per 100 liters. Even at that price an RO unit would pay itself back in a year.

Have you considered anglefish as an alternative? Tons of personality and far less picky

As for different 'species, that is not acceptable since the two main species require vastly different pH's to do well. I assume you mean different 'strains'. Different strains really do fine together.

apologies, i mean different types of discus ie; strains. there wont be other types of fish in the tank.

Never use 'distilled water' alone (same for RO.) Water with near zero minerals is deadly for fish. - if i chose to use distilled water i would add discus minerals as required, im assuming that this would be ok?

Unless you are breeding, soft water is totally unnecessary to keep healthy and happy discus. interesting, if this is the case then perhaps im wasting my time trying to get the bloody hardness down.

Another point: temperature. Discus require a minimum tank temperature of 84 F (29 C) and 86-88 F (30 - 31 C) is better. this is where im finding alot of controversy, some sources say 30-31c where as others including AC information page on discus say 25-29c. at the moment im hovering around 25.5.

However, in your case I do not see the need for such drastic measures. A GH of 7 dGH is not at all bad, and if it does get to 9 you could dilute it a bit with rainwater or pure water. thanks, i will try diluting it with distilled water with added discus minerals to bring the Gh down a bit, i also need to bring the pH down to a reasonable level so diluting with DW should also help.

OK, your vast passage appears like it proves something relative to salt for discus - it does not. I have researched this topic and most experts agree (including PhD's) that salt does and is useful for helping fish remove their waste.

"Within freshwater fish, the kidney is responsible for preventing excess solute loss as they contain more salts within their blood than the water located around thier bodies. Due to this concentration gradient, water will naturally diffuse into the fish through osmosis causing large amounts of water to build up inside. Therefore, the kidneys in this type of fish increase the amount of water that passes out in their urine and actively reabsorb the salts that would pass out as well to maintain that balance. This therefore results in the production and excretion of large amounts of dilute urine. This urine is so dilute that it is almost completely composed of water."

The science behind this:
the density of minerals within the blood of any freshwater fish is higher than the water - period. Hence the gills & kidney's of freshwater fish must do work in order to prevent water from entering their system. That is, for any fish to 'pump' waste out of their system they must use internal water (that is how their kidney's and gills function.) As such, the fish organs MUST do more work in getting waste out of their system when they are in pure water. In water with a higher concentration of minerals these organs do less work - fact.

Hence, adding salt reduces the work both the gills and kidney's must perform in order to remove waste. Can't change reality.

Most of that article is standard knowledge and has no relevancy to what I said and really, has no value for this discussion except as wasted filler (Like I didn't know salt hurts plants? And really, salt increases the dissolved solids ... Duh, obvious. As for some species of fish do not tolerate salt very well, again, this is well known. The fact that most fish can be treated with salt for short times even as the post pointed out - the issue is dose and time; again, duh. That saltwater (ocean) salt cannot be used for freshwater fish - again, DUH! What does that have to do with my post? I said freshwater aquarium salt!

Do I support using salt 100% of the time? Oh, please. Neither did I say that or imply that. It is true that some experts in discus keeping do like adding some salt for old discus. Works for them. I wouldn't.

As for all freshwater fish? No. Some are sensitive to salt and I never indicated using salt regularly was/is or will be good for all fish. Has salt been used by aquarium keepers over the decades? Yes - salt is a common treatment used for ick.

The article even points out the maximum time frame I suggested - two weeks (that is ONLY for discus relative to my advice.)

I really have to laugh about the part in the article you cite says that aquarium keepers are divided on the safety of water softeners ... please. Can the BS just be dropped from articles when you cited them? That usage is just code for "I have no idea on this subject and can't find anyone who does but since this does not support my overall article on the dangers of sodium I need to muddy the waters to make what I'm saying sound better."

You may differ on salt use for discus but the article you in any way prove this practice is dangerous, harmful at all for discus. Further, scientific fact on osmatic pressure proves that it IS helpful to their ability to rid themselves of waste. I have used salt (freshwater aquarium salt) with great results. I learned it from the one of the most famous discus breeders on the East coast (Discus Hans.) That does not prove anything but the scientific fact does prove that salt improves the ability of fish to remove waste from their bodies.

I have more important things to do than waste my time on trying to explain proven scientific fact - one can argue if a given treatment works or for how long but not with fact. If you want to continue this, PM me and when I have time, I'll continue.

Last edited by Cermet; 10-07-2013 at 12:56 PM.

Knowledge is fun(damental)

A 75 gal with eight Discus, fake plants, and a lot of wood also with sand substrate. Clean up crew is down to just two Sterba's Corys. Filters: continuous new water flow; canister w/UV, in-tank algae scrubber!! Finally, junked the nitrate removal unit from hell.